Taking folic acid supplements around the time of conception may lower the risk of autistic disorder in the offspring, an observational study showed.

Compared with women not using the supplements, those taking a folic acid supplement from 4 weeks before to 8 weeks after conception were less likely to have a child later diagnosed with autistic disorder...

In Norway, the recommendation is for all women attempting to become pregnant to take a supplement containing 400 µg of folic acid daily from 1 month before conception through the first trimester. At the time of the study, no foods in Norway were fortified with folic acid. [emphasis mine]